The present invention relates to impellers for compressors, turbines, pumps, fans and the like and in particular to the construction and shape of the blades therefor.
As is well known, the blades of hydrodynamic impellers for fluid or liquid apparata are provided with curved faces to generate a centrifugal force on the fluid. In general, it is known to shape such impeller blades so that their faces are described by angles inscribed between a tangent to a point on the surface of the blade and a tangent to a circle, having its center in the axis of rotation, passing through the point, which angles gradually change in one direction only, throughout the extent of the blade. That is, the angle either increases or remains the same from the leading to the trailing tips of the blade. The blades designed by these known methods appear, when developed into a plane, to be slightly cambered or extend straight, and on the impeller itself take a logarithmic spiral shape. This design is generally thought to be the optimum possible and the resultant hydraulic characteristics of the blades so designed are thought to be incapable of any further significant improvement. However, the angular momentum of the fluid being worked on increases constantly from the inlet to the outlet of the impeller and the fluid progresses from a minimum velocity to a maximum velocity. This angular momentum is expressed by the formula M =.rho. Q (r . Cu), where M is the angular momentum, where .rho. is the specific mass of the fluid being pumped, Q is the quantity of fluid delivered in a given unit time, r is the radius of the impeller, and Cu the component of absolute velocity. Since the absolute velocity is an ever changing factor, maximum efficiency, complete absence of cavitation, vibration and noise have not been obtained even with the so-called optimum design.
It is the object of the present invention to provide an improved impeller construction for hydrodynamic pumping having an improved blade configuration which overcomes the defects and disadvantages of the prior art constructions.
It is a further object of the present invention to provide an improved impeller having greater efficiency, reduction of cavitation, reduction of noise and reduction of pulsation.
It is yet another object of the present invention to provide an improved impeller having blade construction which is simple, easily fabricated, and does not affect the otherwise known construction of the impeller or pump.
The foregoing objects, other objects together with numerous advantages will be apparent from the following disclosure of the present invention.